1. Field of the Invention
The present invention relates to a transparent gas barrier laminate film having both of superior heat resistance and superior gas barrier property, a substrate utilizing the gas barrier laminate film and an image display device such as an organic electroluminescence device (henceforth referred to as an “organic EL device”) and liquid crystal display device utilizing the gas barrier laminate film. In particular, the present invention relates to a substrate and image display device utilizing a flexible support.
2. Description of the Background
With the wide spread of personal computers and portable information terminals, the demand for a thin and light electronic display is rapidly increasing. Currently, glass substrates are mainly used in the liquid crystal display devices, which are most widely spread, and in the organic EL devices, which draw attentions because of their high visibility due to the self-coloring property. In view of production of lighter devices, impact resistance, flexibility and so forth, it is preferred that flexible plastic substrates are used as substrates of liquid crystal devices and organic EL devices. However, plastic substrates have poorer heat resistance and gas barrier property compared with glass substrates. Therefore, they suffer from disadvantages that they are unsuitable for production of highly precise patterns and that their durability is poor.
Many researches to improve such drawbacks of plastic substrates have been reported so far. For example, techniques for improving gas barrier property have been reported in the following patent documents.
Japanese Patent Laid-open Publication (Kokai) No. 2001-205743 (page 3, [0012] to page 10, [0062]) discloses an example of use of a plastic substrate having a multilayer structure constituted by layers comprising layered compounds in a liquid crystal display device. This patent document describes that heat resistance, hardness and anti-gas permeability are improved by the use of the layered compounds. However, the gas barrier property described therein cannot be considered sufficient, and further improvement is required.
Japanese Patent Laid-open Publication No. 7-251489 (page 3, [0005] to page 8, [0034]) discloses a laminated film provided with a layer of a composition comprising a layered inorganic compound having a specific aspect ratio and a resin between layers of polyolefin type resin in order to reconcile moisture proofing property and oxygen barrier property.
Japanese Patent Laid-open Publication No. 2000-343659 (page 2, [0010] to page 7, [0058]) discloses a film having a gas barrier layer comprising a mixture of partial hydrolysate of alkoxide condensate and a water-soluble polymer. However, all of these could not yet provide sufficient oxygen barrier property in high humidity, and the gas barrier property of the whole laminated films needs to be further improved for use in liquid crystal display substrates or organic EL substrates.
Further, for improvement of gas barrier property, a method for producing a gas barrier film comprising providing a layer containing a metal alkoxide or a hydrolysate thereof and then irradiating the layer with an electromagnetic wave to produce a gas barrier film. See, for example, Japanese Patent Laid-open Publication No. 2000-313087 (page 3, [0020] to page 4, [0027]). However, a sufficiently dense film cannot be obtained with a metal alkoxide alone or condensate of metal alkoxide containing a silane coupling agent, and the gas barrier property cannot be considered sufficient for, in particular, use in electronic circuits and display materials.